Some billbaords have been hung on the most highly trafficked places in London.

Google's "DoubleClick" online advertising will soon be taken to digital billboards as the company has already commenced testing the initiative on billboards at multiple places in London.

"DoubleClick" technology, using data gathered in real time, like weather, travel information, audience and local events, selects which ads to run, when they should be run, and even which billboards to play them on.

The reason behind such a move is reportedly to provide passers-by the most appropriate ads for that time of the day as well as the location they're present. In fact, if the passing audience isn't right to be served with an ad, the "DoubleClick" billboards will not show them an ad.

The trial for "DoubleClick" billboards commenced in London in early October, and will run throughout November. The ads are being provided at busy areas in London such as city centres and transport and roadside locations in premium digital screens.

Some such billboards have been hung on the highest-traffic places in the city, such as Euston Road and Waterloo Station.

Google isn't the only company to have started testing this technology. The idea of out-of-home advertising has been tested by many other ad tech companies such as Rubicon Project, Xaxis, and Tube Mogul.

However, the immense success of the "DoubleClick" business puts Google in the driver's seat when it comes to gaining popularity in the public.

Tim Coller, the mobile solutions head for "DoubleClick", said it is a "common misconception" that conjoining online advertising and billboards is "straightforward".

"This test has highlighted a number of areas that are fundamentally different and will require further development and integration before this becomes a market reality. For example: Serving dynamic creative, how we look at impressions versus credits, reporting, audience data, buying models, yield management, and latency," he said, according to Business Insider.

Coller explained that Google's aim through the "DoubleClick" billboards is to know if they can utilise the media it buys more effectively across several portfolios of its brands.

"If we buy a million credits that would normally be served to one advertiser with a degree of wastage, can we better utilise that same million impressions across all of our advertisers to drive maximum efficiency?" he added.